1. Field of the Invention
The present invention relates generally to a regenerator device in an optical network, and particularly to a flexible bit rate clock recovery unit for use in the regenerator device.
2. Technical Background
Regenerators are used in optical communication systems to prevent the accumulation of signal distortion. A regenerator typically performs re-amplification, re-shaping and re-timing functions on an incoming data signal. In order to perform the re-timing function, it is necessary to extract the clock signal associated with the incoming data signal.
Conventional clock recovery units have only limited tuning range (e.g., typically less than 1% of the clock rate). This type of clock recovery unit does not pose a problem for optical communication systems which operate at a single bit rate. However, today's optical communication system must support input data signals transmissible at a variety of different bit rates.
Therefore, it is desirable to provide a clock recovery unit for recovering clock signals from input data signals transmissible at a variety of different bit rates. The clock recovery unit should identify the bit rate of the incoming data signal and extract the clock signal from it so that the incoming data signal can be correctly re-timed for retransmission.